A refrigerator refers to an apparatus that includes a storage compartment therein to store items such as, for example, food and serves to generate cold air using a refrigeration cycle and to supply the cold air to the storage compartment so as to keep the stored items at a low temperature for a long term.
The refrigerator uses the refrigeration cycle to generate the cold air to be supplied to the storage compartment. The refrigeration cycle consists of a compression process, a condensation process, an expansion process, and an evaporation process, and refrigerant from the evaporation process is again routed back to the compression process.
Considering the refrigeration cycle in detail, the compression process is a process in which high temperature and low pressure gas-phase refrigerant is changed into high temperature and high pressure gas-phase refrigerant by a compressor, the condensation process is a process in which the high temperature and high pressure gas-phase refrigerant is changed into middle temperature and high pressure liquid-phase refrigerant by a condenser, the expansion process is a process in which the middle temperature and high pressure liquid-phase refrigerant is changed into low temperature and low pressure liquid-phase refrigerant by an expansion valve, and the evaporation process is a process in which the low temperature and low pressure liquid-phase refrigerant is changed into high temperature and low pressure gas-phase refrigerant by an evaporator.
Accordingly, in the evaporation process of the refrigeration cycle, the refrigerant absorbs external heat, causing the surrounding air to be cooled and kept at a low temperature. The resulting cold air is supplied to the storage compartment.
The refrigerator generally includes a freezing compartment, the temperature of which is set to lower than zero degrees in order to keep stored items frozen, and a refrigerating compartment, the temperature of which is set to be lower than room temperature in order to keep stored items fresh.
In general, drinking water, beverages and the like are stored in the refrigerating compartment. When it is required to open the refrigerator door whenever a user retrieves drinking water stored in the refrigerating compartment, this causes frequent discharge of cold air from the storage compartment, resulting in wasted energy.
To solve this problem, in the related art, a water tank is provided at the rear surface of the door to penetrate the door so as to allow the user to drink the water stored in the water tank.
However, the related art has problems in that separating or coupling the water tank from or to the rear surface of the door is difficult because of the weight of water stored in the water tank and in that cold air inside the storage compartment may leak outward through a water tank penetration region in the door formed from the inside to the outside.